Telephone system



Dec. 8, 1931. c. A. ANDERSON Q 1,335,256

TELEPHONE SYSTEM Original Filed July 20, 1927 2 Sheets-Sheet l ET-UP CODE RELAYS j ff g I1T r e'FlEF- U Clarence H.5ndarsmn Dec. 8, 1931. i c, ANDE$ON 1,835,256

TELEPHONE SYSTEM Original Filed July 20, 1927 2 Sheets-Sheet 2 UN/ T5 HUNDREDS POLAR/ZED Im'afi Clarence H.5ndersun Patented Dec. 8, 1931 UNITED STATES PATENT OFFICE CLARENCE A. ANDERsoN oF CHICAGO, ILLINOIS, ASSIGNOR, BY MESN'E ASSIGNMENTS,

TO AMERICAN ELECTRIC COMPANY, INC., OF CHICAGO, ILLINOIS, A. CORPORATION.

OF DELAWARE 'rELnrnoN'E SYSTEM Original application filed July 20, 1927, Serial No. 207,161. Divided and this application filed January The present invention relates to telephone systems in general, but more particularly .to telephone systems employing call indicators for indicating to an operator the destination of calls.

The present invention discloses novel sending means and novel receiving means for sending and receiving impulses corresponding to desired telephone numbers and for displaying these numbers before an operator, and has been applied to a telephone system wherein one or more trunk lines connect two telephone exchanges.

An object of the invention is the production of new and improved circuit arrangements whereby codes of impulses of different strength and polarities may be transmitted upon the depression of a digit key corresponding to a digit desired to be sent over a telephone line.

Another object of the invention is the production of new and improved relay arrangements in connection with the keys at the transmitting end of the circuit whereby a plurality of impulses may be sent out upon a single operation of a key, and whereby a 'suffi; v cien't space is provided between successive" impulses to permit a switching operationto be accomplished at the receiving end of the circuit. 1

Another object of the invention is the production of new and improved arangements at the receiving end of a telephone line to enable a reduction to be made in the number of spring contacts on the register relays in the receiver by arranging the receiving lamp banks in interconnected squares and by applying one potential to a vertical conductor of an interconnected square and another potential to a horizontal conductor to light the particular lamp common to both conductors.

Another object of the invention has to do with a reduction in the number of receivingrelays required by suitably arranging a single relay to carry the spring contacts ordinarily carried bytwo relays and to cause the relay to differentiate between which of the two functions it is to perform by arranging it to operate through one'step or through two steps as the occasion demands.

Serial No. 511,209.

Another object of the invention is the production of a new and improved arrangement for operating the transfer relays used to transfer the receiving conductors from one set of receiving circuits to another as the code impulses are received. I

There are other objects and features of the invention having to do moreor less with the circuit details involved in carrying out the foregoing. The various objects and features of the invention can be understood best from a further perusal of the specification in connection with the accompanying drawings.

The present application is a division of my application, 207,161, filed July 20,1927. The present application is limited to the novel features of the improved impulse sender, the remaining features having been claimed in the parent application.

Referring now to the accompanying drawings comprising Figs. 1-3, Figs. 1 and 2 are circuit diagrams showing a sufiicient amount of apparatus involved in a telephone system embodying the features of the invention to enable. the invention to be understood, and Fig. 3 is a table showing the code according to which the impulses are transmitted ,and indicating the relays which respond tothe various transmitted impulses.

' Fig. 1 shows the outgoing end of a trunk line between twoexchanges, together with the sending keys and the associated equipment.

" i Fig. 2 shows the incoming end of the trunk line in the second exchange including the various receiving relays and lamp sets.

Referring particularly to Fig. 3, which inthe. positive sign of the digit 2 is-made heavier than the positive sign of the digit 1, the positive impulse of the digit 1 is light, while the positive impulse of the digit 2 is heavy.

Similarly, a positive impulse and a 'nega- I I tive impulse represent the digit 3, but in this case both impulses are heavy. The distinction between heavy impulses and light impulses is made according to whether a re sistance, such as the resistances 21 and 22, Fig. 1, is included in the impulsing circuit at the time the impulse is sent. A positive impulse, it may be pointed out, is one sent from the positive battery 24, while a negative impulse is one sent from the negative battery 23.

Still referring to Fig. 3, it will be noted that the relay A of the connected set operated in response to the positive impulse of the digit 1, but it will be noted that no relay is operated in response to the negative impulse. The reason for this will appear subsequently. It will be noted further that relays A and C respond in the connected set when the heavy positive impulse of the digit 2 is transmitted. It may be pointed out that the reference character C is used to indicate that relay C of the connected set operates through its first step. The. same response of the relays A and C occurs when the heavy positive impulse of the digit 3 is transmitted. and relay C2 responds to the heavy negative impulse of the digit 3. The reference char 1'. r C2is meant to indicate that relay C of the connected set operates through its second step.

The invention having been discussed in general a detailed descr ption will now be given. For this purpose it will be assumed that the operator in the first exchange receives a call for a connection to be extended to a line terminating in the second exchange. In order to extend the connection, the operator 1n the first exchange inserts the plug 'of a cord circuit (not shown) into the jack conductor 25 is grounded at the inner right-' hand contacts of the key, and a heavy negative impulse is placed on conductor 26 at the inner left-hand contacts of the key through the contacts of relay 11. outer right-hand contacts of the key K9, a circuit is closed for relay 19. Relays 19, as well as relay 20, is slightly slow to operate due to a stiff spring adjustment and due to a copper collar on the armature end of the core.

After a light interval of time has elapsed (suflicient to allow a full impulse to be transmitted), relay 19 operates and terminates the heavy negative impulse by disconnecting conductor 26 from the heavy negative impulse conductor extending up from the bat- At thetery 23. Relay 19 also closes a circuit for the auxiliary relay 20. After an interval sufficiently long to permit switching'operations hereinafter described to take place, the slightly slow-to-operate relay 8 operates and places a heavy positive impulse on conductor 26 through the outer left-hand contacts of the depressed key K9.

After having held the key K9 depressed for a sufficient interval, the operator releases the key, thereby terminating the heavy positive impulse and opening the circuit of relays 19 and 20. These relays fall back quickly due to their stiff spring adjustment.

\Vhen the operator depresses the key K10 to transmit the digit 0, two light negative impulses are transmitted through the bat tery 23 and the resistance 21, relays and 19 operating as above described.

When the operator depresses the key K4 to transmit the digit 4, two light positive impulses are transmitted from the battery 24 through the resistance 22 by the action of the relays 20 and 19.

After the operator has finished transmitting the code impulses, the keys are all in the position shown and the trunk line com prising conductors 25 and 26 is clear for voice-current transmission.

Referring now to Fig. 2, when the heavy negative impulse of the digit 9 passes through the receiving relays 51-53, the marginal relay 53 and relay 52 are operated, but the positively polarized relay 51 is not operated by the negative impulse. When the marginal relay 53 is operated, a circuit is closed for relay C1 through the lower armature of relay 55 and the resistance associated with relay C1. When operated through the associated resistance, relay C1 operates through its first step only, operating its lefthand armatures. At its inner left-hand armature, relay C1 closes a locking circuit for itself through the associated resistance, and at its, outer left-hand armature it removes ground from the vertical conductor common to the lamps 1, 4, and 7 and places ground on the conductor common to the lamps 2, 5, and 8 through the right'hand armature of the relay, which armature shifts only when the relay is operated through its second step.

When the relay 52 responds to the impulse, it opens the circuit of the upper winding of the differential relay 55 and connects the upper winding of relay 55 in multiple with the winding of the auxiliary relay 5 4. Relay 55 now energizes through its lower winding from ground on the locking conductor through the release button RB. Relay 55 is adjusted so that its inner upper armature is very sensitive and operates first. The remaining armatures of the rela are rather stifily adjusted with the result t at the relay hesitates for an appreciable length of time the operating conductor before operating further after the lightly ad- 'usted inner upper armature has operated. l Vhen this armature operates,:it disconnects 75 from the upper winding of relay 55 and connects it to ground through the adjacent upper armature, which as is noted on the drawings breaks contact last, that is, after all other armatures of the relay have operated. During the interval required for the relay to complete its operation after the inner upper armature has shifted, as above described, relay 54 is, operated from ground on conductor 75 through the operated contacts of relay 52. When relay 54 operates it locks itself operated by placing a multiple ground connection on conductor 75 so that it will remain operated and maintain conductor 7 grounded as long as the impulse endures and maintains relay 52 operated.

When relay 55 has operated fully, it breaks the-ground connection (at its break-last contacts) from the extension of operating conductor 75, which would allow the current to cease flowing in the upper winding of the difierential relay 56 if it were not for the multiple ground connection on conductor 75 at the auxiliary relay 54. Relay 52 falls back at the end of the impulse, as does the marginal relay 53 and opens the circuit of relay 54:, at the same time replacing the normal ground connection on conductor 75. Re-

, lay 5% now falls back, leavingconductor 75 grounded only at the normal contacts of relay 52. This ground potential on conductor 75 maintains the difi'erential relay 56 nonoperated.

As a further result of the operation of relay 55, it transfers the relay-operating circuit controlled by the marginal relay 53 from the circuit of relay C1, through the associated resistance, through the lower armature of relay 56 to the winding of relay 61 direct. Relay also makes a similar transfer of the relay operating conductors controlled by the polarized relay 51 fromrelay A1 to relay 181 through the upper contacts of relay 56. At its upper armature, relay @5 closes a circuit tor the (l lamp through contacts of the nonoperated relays A1 and B1. As a result, the 0 lamp is lighted unless-one or the other of the relays A1 and B1 is operated, as will now take lace. p en the heavy positive impulse of the digit 9 is received by the'receiving relays, all three relays operate. The marginal relay 53 closes a circuit through the lower armature, operated, of relay 55 and through the lower armature, normal, of relay 56 for the relay $01 independent of the associated resistance.

As a result, relay C1 operates through its second step, and remains operated through its second step even afterthis circuit is opened, owing to the fact that the current flow through the associated resistance and through the locking contacts of the relay is suflicient to maintain the relay completely operated after it has once been operated fully. The right-hand armature of relay C1 transfers the ground potential from the vertical conductor common to the lamps 2, 5, and 8 to the vertical conductor common to the lamps 3, 6, and 9. J

When the positively polarized relay 51 operates, it closes a circuit through the corre. sponding armature, operated, of relay 55 and through the upper armature, normal, of re lay 56 for the left-hand winding of relay B1. Relay B1 operates and locks itself to the associated locking conductor and at its left-hand armature it opens the circuit of the O lamp, and places battery through the inner armature, normal, of relay 8 on the horizontal conductor common to the lamps 7, 8, and 9. After this, the full potential is across the terminals of the lamp 9, and this lamp is lighted. An examination will show that there is a slight current flowing through each of the other lamps due to the way in which the common conductors are connected to the lamps, but the potential across no other lamp is equal to halt the full potential. The result is that the standard switchboard lam s assumed to be used they are usually of t e carbon filament type fail to light, with the exception of the lamp 9.

When the transfer control relay 52 re sponds, it removes ground from conductor 7 5 and connects this conductor to the auxiliary relay 54. As a result, relay 56 operates in the same manner as described in connection with relay 55 and transfers conductor 7 5 to relay 57. The auxiliary relay 54, as before, maintains conductor grounded as long as relay 52 remains operated, so as to prevent the next relay in the transfer chain from operating prematurely. llhe operating circuit-s controlled by the receiving relays are now transferred through contacts of relay 57 to the tens register.

When the first light negative impulse of the digit 0 is received, receiving relay 52 alone responds, relay 53 being marginalv and rela 51 being positively polarized.

pon responding, relay 52 aided by the auxiliary relay, 54, brings about the operation of relay 57, whereupon circuits are transferred to relay 58. A circuit is closed for the 0 lamp of the tens set at the upper contacts of relay 57, whereupon the 0 lamp becomes lighted.

When the second light negative impulse of the digit 0 is received, receiving relay 52 responds alone and brings about the operation of the transfer relay 58, whereupon the op erating circuits are transferred to relay 59. As none of the relays A2C2 are operated, the lamp 0 is lighted alone and the lamps 1-9 are not lighted.

When the first light positive impulse of the operating the digit 4 is received, relays 52 and 51 both respond, and relay 51 closes a circuit through the associated contacts of relays S L-59 for the left-hand winding of relay A3. Relay A3 operates and closes a locking circuit for itself at its right-hand armature, and at its outer-left-hand armature it removes battery from the lower terminal of the 0 lamp and places battery on the horizontal conductor common to the lamps 1, 2, and 3. Relay 59 responds in the hereinbefore described manner to the operation of the transfer control relay 52.

When the second light positive impulse of the digit 4 is received, relays 51 and 52 respond as before. and relay 51 closes at this time a circuit through the associated contacts of relays 54-60 for the left-hand winding of relay B3. Relay B3 operates and locks itself, at the same time transferring the battery potential from the horizontal conductor common to lamps 1, 2, and 3 to the conductor common to the lamps 4c, 5, and 6. Relay responds to the operation of relay 52 and disconnects the operating conductors from the windings of the relays B3 and C3. Since battery is now placed through the contacts of the operated relays A3 and B3 on the horizontal conductor common to lamps 4, 5, and 6, and, since relay C3, being non-operated, permits the ground potential to remain on the conductor common to lamps 1, 4, and 7, the lamp 4 alone is lighted.

As a result of the foregoing operations, the ninth lamp in the hundreds set, the tenth lamp in the tens set, and the fourth lamp in the units set are lighted to display to the operator the desired number 904. The operator in this exchange may now insert the plug of a cord circuit into the jack J2 and complete the desired connection.

After the operator has noted the desired number, she releases the operated equipment by momentarily operating the release button RB. whereupon the locked up relays fall back, extinguishing the lighted lamps and restoring the circuits tomorrnal. 7

When the conversation is terminated, as may be discovered by the operator in the originating exchange by listening in in the usual manner, the originating operator may transmit a disconnect number over the exchange trunk line comprising conductors 25 and 26. This disconnect number may be some arbitrary number such as, for example, 111, or perhaps 000.

Upon perceiving the disconnect number transmitted over the interexchange trunk line by the operator inthe first exchange, the operator in the second exchange may release the indicating equipment and take down the connection. The connection in the first exchange is taken down by the operator therein.

From-the foregoing description, it will be obvious how the other digits are transmitted when desired.

It will be apparent that relay C1 may be replaced, if desired, by two relays, each relay carryin locking contacts, one relay carrying the rst-step switching contacts and the other relay carrying the second-step switching contacts. The first relay would, of course, be operated overthe conductor connected to the back contact of the lower armature of relay 55, and the second relay would, of course, be connected to the conductor extending from the back contact of the lower armature of relay 56. The same arrangement may be applied to the relays C2 and C3.

What is claimed is 1. In a telephone-system, an interchange trunk line, a set of digit keys, and relay mechanism responsive to the operation of said digit keys for transmitting through the contacts of said keys impulses corresponding to the digits represented by said keys.

2. In combination, a set of keys, each representing aseparate digit, relays controlled by said keys, and means responsive to the actuation of any key for operating said relay mechanism. to transmit impulses of a polarity and strength corresponding to the digit assigned to the depressed key according to a preassigned code.

3. In combination, a conductor forming part of an impulse circuit, a manually operable key, contacts on said key for placing an impulse of predetermined polarity and strength on said conductor, and a relay controlled by other contacts of said key for terminating said impulse.

4. In combination, an impulse conductor, a manually operable key having contacts, means responsive to an operation of said key for placing an impulse of predetermined strength and polarity on said impulse conductor, means including relay mechanism controlled through other contacts of the operated key for terminating said impulse after a predetermined interval has elapsed and for placing a second impulse of redetermined strength and polarity on sai impulse conductor after the elapse of a further predetermined interval.

5. In combination, digit keys each having a plurality of contact pairs arranged to close when the key is operated, two sending circuits, one circuit being closed by one contact pair when the key is operated and the other being prepared, a set of responding relays included in both circuits and responsive to a closure of either circuit, delayed action means, and means including another of said contact pairs for operating the delayed action means to open the first circuit after the relay set has had time to respond to the closure of the first circuit and to subsequently operate it to close the second circuit after the relay set has had time to restore responsive to the opening of the first circuit. 3

6. In combination, a set of keys each representing a separate digit, sending means associated with said keys, and means respom sive to the actuation of any key for operating said sending mechanism while the key is actuated to transmit im ulses of a polarity and strength correspon ing to the digit as: signed to the depressed key according to a preassigned code. 4

7. In combination a set of di 't keys, there being a separate digit assign to each key, sending means arranged to transmit digits according to a preassigned code wherein each digit is represented by a different combination of impulses of different characters, and means effective when said digit keys are momentarily and successively depressed for operating said sending mechanlsm during the momentary depression of each of said keys to transmit the impulses of the character combination assigned to the digit represented by the depressed key.

8. In a signalling s stem, a signal line over which character com inations are to be successively transmitted as respective units in a signal code, a set of keys, there being a separate one of said combinations assi ed to each of said keys, and means responslve to a momentar actuation of any-oneof said keys and effectlve while the key is actuated for transmittin the character combination over said line w key.

9. In a signalling stem, a signal line over which character com inations are to be successively tranmitted as respective units in a signal code, a set of ke s, there being a separate one of said com inations assigned to each of said keys, and means responsive to successive momentary actuations of said keys for sendin in each case while the key is actuated the c aracter combination assigned to the actuated key.

In witness whereof, I- hereunto subscribe my name this 23d day of January, A. D. 1931.

CLARENCE A. ANDERSON.

ich is assigned to the actuated- 

